Alluri Ram K, Bougioukli Sofia, Stevanovic Milan, Ghiassi Alidad
Department of Orthopaedic Surgery, Keck Medical Center of University of Southern California, Los Angeles, CA.
Department of Orthopaedic Surgery, Keck Medical Center of University of Southern California, Los Angeles, CA.
J Hand Surg Am. 2017 Sep;42(9):748.e1-748.e8. doi: 10.1016/j.jhsa.2017.05.010. Epub 2017 Jun 7.
To compare the biomechanical properties of second versus third metacarpal distal fixation when using a radiocarpal spanning distraction plate in an unstable distal radius fracture model.
Biomechanical evaluation of the radiocarpal spanning distraction plate comparing second versus third metacarpal distal fixation was performed using a standardized model of an unstable wrist fracture in 10 matched-pair cadaveric specimens. Each fixation construct underwent a controlled cyclic loading protocol in flexion and extension. The resultant displacement and stiffness were calculated at the fracture site. After cyclic loading, each specimen was loaded to failure. The stiffness, maximum displacement, and load to failure were compared between the 2 groups.
Cyclic loading in flexion demonstrated that distal fixation to the third metacarpal resulted in greater stiffness compared with the second metacarpal. There was no significant difference between the 2 groups with regards to maximum displacement at the fracture site in flexion. Cyclic loading in extension demonstrated no significant difference in stiffness or maximum displacement between the 2 groups. The average load to failure was similar for both groups.
Fixation to the third metacarpal resulted in greater stiffness in flexion. All other biomechanical parameters were similar when comparing distal fixation to the second or third metacarpal in distal radius fractures stabilized with a spanning internal distraction plate.
The treating surgeon should choose distal metacarpal fixation primarily based on fracture pattern, alignment, and soft tissue integrity. If a stiffer construct is desired, placement of the radiocarpal spanning plate at the third metacarpal is preferred.
在不稳定桡骨远端骨折模型中，比较使用桡腕跨关节撑开钢板时，第二掌骨远端固定与第三掌骨远端固定的生物力学特性。
使用标准化的不稳定腕部骨折模型，对10对匹配的尸体标本进行桡腕跨关节撑开钢板的生物力学评估，比较第二掌骨远端固定与第三掌骨远端固定。每个固定结构在屈伸方向上接受可控的循环加载方案。计算骨折部位的位移和刚度。循环加载后，对每个标本加载直至破坏。比较两组之间的刚度、最大位移和破坏载荷。
在屈曲方向的循环加载显示，与第二掌骨相比，第三掌骨的远端固定导致更大的刚度。两组在屈曲时骨折部位的最大位移方面无显著差异。在伸展方向的循环加载显示，两组在刚度或最大位移方面无显著差异。两组的平均破坏载荷相似。
第三掌骨固定在屈曲时导致更大的刚度。在用跨关节内撑开钢板稳定桡骨远端骨折时，比较第二掌骨或第三掌骨的远端固定，所有其他生物力学参数相似。
治疗外科医生应主要根据骨折类型、对线情况和软组织完整性选择掌骨远端固定。如果需要更坚固的结构，桡腕跨关节钢板放置在第三掌骨处更佳。
